ExoClock Project III: 450 new exoplanet ephemerides from ground and space observations

The ExoClock project has been created with the aim of increasing the efficiency of the Ariel mission. It will achieve this by continuously monitoring and updating the ephemerides of Ariel candidates over an extended period, in order to produce a consistent catalogue of reliable and precise ephemerides. This work presents a homogenous catalogue of updated ephemerides for 450 planets, generated by the integration of $\sim$18000 data points from multiple sources. These sources include observations from ground-based telescopes (ExoClock network and ETD), mid-time values from the literature and light-curves from space telescopes (Kepler/K2 and TESS). With all the above, we manage to collect observations for half of the post-discovery years (median), with data that have a median uncertainty less than one minute. In comparison with literature, the ephemerides generated by the project are more precise and less biased. More than 40\% of the initial literature ephemerides had to be updated to reach the goals of the project, as they were either of low precision or drifting. Moreover, the integrated approach of the project enables both the monitoring of the majority of the Ariel candidates (95\%), and also the identification of missing data. The dedicated ExoClock network effectively supports this task by contributing additional observations when a gap in the data is identified. These results highlight the need for continuous monitoring to increase the observing coverage of the candidate planets. Finally, the extended observing coverage of planets allows us to detect trends (TTVs - Transit Timing Variations) for a sample of 19 planets. All products, data, and codes used in this work are open and accessible to the wider scientific community.Comment: Recommended for publication to ApJS (reviewer's comments implemented). Main body: 13 pages, total: 77 pages, 7 figures, 7 tables. Data available at http://doi.org/10.17605/OSF.IO/P298

ExoClock Project. III. 450 New Exoplanet Ephemerides from Ground and Space Observations

The ExoClock project has been created to increase the efficiency of the Ariel mission. It will achieve this by continuously monitoring and updating the ephemerides of Ariel candidates, in order to produce a consistent catalog of reliable and precise ephemerides. This work presents a homogenous catalog of updated ephemerides for 450 planets, generated by the integration of ∼18,000 data points from multiple sources. These sources include observations from ground-based telescopes (the ExoClock network and the Exoplanet Transit Database), midtime values from the literature, and light curves from space telescopes (Kepler, K2, and TESS). With all the above, we manage to collect observations for half of the postdiscovery years (median), with data that have a median uncertainty less than 1 minute. In comparison with the literature, the ephemerides generated by the project are more precise and less biased. More than 40% of the initial literature ephemerides had to be updated to reach the goals of the project, as they were either of low precision or drifting. Moreover, the integrated approach of the project enables both the monitoring of the majority of the Ariel candidates (95%), and also the identification of missing data. These results highlight the need for continuous monitoring to increase the observing coverage of the candidate planets. Finally, the extended observing coverage of planets allows us to detect trends (transit-timing variations) for a sample of 19 planets. All the products, data, and codes used in this work are open and accessible to the wider scientific community

A surrogate measure of stomatal aperture

It is proposed that a measurement of the peristomatal criterion for choosing a technique is scale of measurement: groove distance (PGD) of guard cells on surface depending on the purpose of the study, researchers may impressions of leaf epidermis can act as a surrogate wish to investigate the conductances of canopies, plants, measure of stomatal aperture. To test this idea, leaves, and sub-leaf areas, or the widths of individual investigations were carried out on two species, one in pores (van Gardingen et al., 1997). The characterization which it is possible to make direct measurements of of patches and trends in stomatal aperture over leaf pore width with relative ease (Commelina communis surfaces (Terashima et al., 1988; Downton et al., 1988; L.) and one whose stomata are so small that this is Smith et al., 1989) has renewed interest in methods difficult (Phaseolus vulgaris L.). Leaf water vapour appropriate for the whole leaf scale and below. Despite conductance measurements were first taken with a the fact that advances in IRGA-based porometry and porometer, then, without delay, a silicone rubber measurement of chlorophyll fluorescence allow direct and impression of the leaf was made of the area directly indirect measurement of stomatal activity in small areas under the porometer cup. From a positive replica of of leaves (Daley et al., 1989; Parkinson et al., 1990), this impression, stomatal aperture, PGD and pore there is still a need for accurate measurements of indi

The model of product distortion in AWJ cutting

V článku uvedeno Libor M. HlaváčThe abrasive water jet (AWJ) retardation inside the cut material, the characteristic phenomenon of the AWJ cutting, causes declination of the kerf sidewalls especially in corners and curvatures. This paper is aimed at a description of the origin of these negative consequences of jet retardation. The model for calculation of the limit traverse speed from both the jet parameters and material properties has been derived using laws of conservation. The equation expressing dependence of the angle between the tangent to the striation curve and the impinging jet axis on the depth of jet penetration into material has been used for evaluation of the product distortion in the cutting process. Proposed model has been applied for setting up the tilting angle of the cutting head during the AWJ cutting process to reduce the product shape distortion. The model was supplemented by geometrical analysis of curved parts of cut trajectories. The resulting equation makes possible to calculate the shift of the jet trajectory at the outlet side of the workpiece from its regular position determined by projection of the trajectory at the inlet side of the workpiece along the jet axis. The model is capable to determine the appropriate tilting angles of the cutting head for compensation of the jet retardation and the taper. The experimental data measured on metal samples seem to be in a good accordance with the proposed model.Web of Science621-416615